The subject matter of the present disclosure broadly relates to the art of suspension systems disposed between sprung and unsprung masses and, more particularly, to suspension systems that can include one or more gas spring and gas damper assemblies as well as a pressurized gas system and a control system operative to selectively transition the one or more gas spring and gas damper assemblies between a spring and damper functionality and an actuator functionality. Methods of operating such suspension systems are also included.
The subject matter of the present disclosure may find particular application and use in conjunction with components for wheeled vehicles, and will be shown and described herein with reference thereto. However, it is to be appreciated that the subject matter of the present disclosure is also amenable to use in other applications and environments, and that the specific uses shown and described herein are merely exemplary. For example, the subject matter of the present disclosure could be used in connection with suspension systems for non-wheeled vehicles and/or support structures and height adjusting systems associated with industrial machinery, components thereof and/or other such equipment. Accordingly, the subject matter of the present disclosure is not intended to be limited to applications and/or uses associated with suspension systems of wheeled vehicles, which as discussed herein are merely exemplary.
Wheeled motor vehicles of most types and kinds include a sprung mass, such as a body or chassis, for example, and an unsprung mass, such as two or more axles or other wheel-engaging members, for example, with a suspension system disposed therebetween. Typically, such a suspension system will include a plurality of spring devices as well as a plurality of damping devices that together permit the sprung and unsprung masses of the vehicle to move in a somewhat controlled manner relative to one another. Generally, the plurality of spring elements function to accommodate forces and loads associated with the operation and use of the vehicle, and the plurality of damping devices are operative to dissipate undesired inputs and movements of the vehicle, particularly during dynamic operation thereof. Movement of the sprung and unsprung masses toward one another is normally referred to in the art as jounce motion while movement of the sprung and unsprung masses away from one another is commonly referred to in the art as rebound motion.
In some cases, a vehicle or other installation, such as has been referred to above, can include a suspension system with components and/or assemblies that are selectively deployable, such as by being capable of selective extension and retraction relative to an associated sprung or unsprung mass. In many cases, such selectively deployable assemblies take the form of axle and wheel sets that are commonly referred to as lift axles. Non-limiting examples of vehicles that can include one or more selectively deployable axle and wheel sets can include over-the-road tractors, over-the-road trailers, dump trucks and concrete mixing trucks. In some cases, such axle and wheel sets can be selectively deployed by a vehicle operator, such as by providing additional support to the body by engaging the wheels with the road surface and thereby increasing the load capacity of the vehicle or re-distributing the weight or load on the truck or trailer.
A variety of suspension systems have been devised and are commonly used to operatively connect an unsprung mass (e.g., a lift axle) to a sprung mass (e.g., a truck or trailer body). Commonly, selectively actuatable suspension systems include one or more springs that bias the lift axle into an extended position under in a deployed condition of the suspension system. In many cases, known suspension systems also include one or more dampers that are operative in the deployed condition of the lift axle and act to dissipate energy associated with undesired inputs and movements of the sprung mass, such as road inputs occurring under dynamic operation of a vehicle, for example. Typically, such dampers are liquid filled and operatively connected between the sprung and unsprung masses, such as between the truck or trailer body and the lift axle, for example. One example of such damping components are conventional shock absorbers that are commonly used in vehicle suspension systems.
One disadvantage of known constructions is that the one or more dampers that are operatively connected between the sprung and unsprung masses are often used only in deployed condition of the selectively actuatable suspension system. As described above, in a deployed condition, the one or more dampers act to dissipate kinetic energy acting on the vehicle or other installation. In a retracted condition, however, the one or more dampers may be collapsed into a non-functioning condition and, thus, represent added weight that can reduce the transportable payload of an associated vehicle.
Additionally, it will be appreciated that conventional constructions typically include primary springs that function to actuate the suspension system into a deployed condition and also provide the primary biasing or spring force for the suspension system in the deployed condition. In many cases, known suspension systems are constructed such that the primary springs are largely incapable of lifting or otherwise retracting the lift axle or other unsprung mass from the deployed position into a storage condition. As such, conventional constructions commonly include one or more secondary springs that are selectively actuatable to retract the suspension system from a deployed condition. In addition to the added weight of the secondary springs and the associated components, such secondary springs can contribute to increased costs, added maintenance, increased space usage and/or other disadvantageous characteristics of conventional suspension systems that include selectively deployable components and/or assemblies.
Notwithstanding the widespread usage and overall success of conventional suspension systems that are known in the art, it is believed that a need exists to meet these and/or other competing goals while still retaining comparable or improved performance, ease of manufacture, ease of assembly, ease of installation, reduced cost of manufacture and/or otherwise advancing the art of suspension systems.